/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.validation.beanvalidation;

import java.lang.reflect.Method;
import java.util.Set;
import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import javax.validation.executable.ExecutableValidator;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.ClassUtils;
import org.springframework.validation.annotation.Validated;

/**
 * An AOP Alliance {@link MethodInterceptor} implementation that delegates to a
 * JSR-303 provider for performing method-level validation on annotated methods.
 *
 * <p>Applicable methods have JSR-303 constraint annotations on their parameters
 * and/or on their return value (in the latter case specified at the method level,
 * typically as inline annotation).
 *
 * <p>E.g.: {@code public @NotNull Object myValidMethod(@NotNull String arg1, @Max(10) int arg2)}
 *
 * <p>Validation groups can be specified through Spring's {@link Validated} annotation
 * at the type level of the containing target class, applying to all public service methods
 * of that class. By default, JSR-303 will validate against its default group only.
 *
 * <p>As of Spring 5.0, this functionality requires a Bean Validation 1.1 provider.
 *
 * @author Juergen Hoeller
 * @see MethodValidationPostProcessor
 * @see javax.validation.executable.ExecutableValidator
 * @since 3.1
 */
public class MethodValidationInterceptor implements MethodInterceptor {

    private final Validator validator;


    /**
     * Create a new MethodValidationInterceptor using a default JSR-303 validator underneath.
     */
    public MethodValidationInterceptor() {
        this(Validation.buildDefaultValidatorFactory());
    }

    /**
     * Create a new MethodValidationInterceptor using the given JSR-303 ValidatorFactory.
     *
     * @param validatorFactory the JSR-303 ValidatorFactory to use
     */
    public MethodValidationInterceptor(ValidatorFactory validatorFactory) {
        this(validatorFactory.getValidator());
    }

    /**
     * Create a new MethodValidationInterceptor using the given JSR-303 Validator.
     *
     * @param validator the JSR-303 Validator to use
     */
    public MethodValidationInterceptor(Validator validator) {
        this.validator = validator;
    }


    @Override
    @SuppressWarnings("unchecked")
    public Object invoke(MethodInvocation invocation) throws Throwable {
        Class<?>[] groups = determineValidationGroups(invocation);

        // Standard Bean Validation 1.1 API
        ExecutableValidator execVal = this.validator.forExecutables();
        Method methodToValidate = invocation.getMethod();
        Set<ConstraintViolation<Object>> result;

        try {
            result = execVal.validateParameters(
                    invocation.getThis(), methodToValidate, invocation.getArguments(), groups);
        } catch (IllegalArgumentException ex) {
            // Probably a generic type mismatch between interface and impl as reported in SPR-12237 / HV-1011
            // Let's try to find the bridged method on the implementation class...
            methodToValidate = BridgeMethodResolver.findBridgedMethod(
                    ClassUtils.getMostSpecificMethod(invocation.getMethod(), invocation.getThis().getClass()));
            result = execVal.validateParameters(
                    invocation.getThis(), methodToValidate, invocation.getArguments(), groups);
        }
        if (!result.isEmpty()) {
            throw new ConstraintViolationException(result);
        }

        Object returnValue = invocation.proceed();

        result = execVal.validateReturnValue(invocation.getThis(), methodToValidate, returnValue, groups);
        if (!result.isEmpty()) {
            throw new ConstraintViolationException(result);
        }

        return returnValue;
    }

    /**
     * Determine the validation groups to validate against for the given method invocation.
     * <p>Default are the validation groups as specified in the {@link Validated} annotation
     * on the containing target class of the method.
     *
     * @param invocation the current MethodInvocation
     * @return the applicable validation groups as a Class array
     */
    protected Class<?>[] determineValidationGroups(MethodInvocation invocation) {
        Validated validatedAnn = AnnotationUtils.findAnnotation(invocation.getMethod(), Validated.class);
        if (validatedAnn == null) {
            validatedAnn = AnnotationUtils.findAnnotation(invocation.getThis().getClass(), Validated.class);
        }
        return (validatedAnn != null ? validatedAnn.value() : new Class<?>[0]);
    }

}
